Oracle Tidbits – May 2016

Oracle *daily* TidBits” (#oratidbit) published at on weekdays in May 2016. You will also see these tidbits, one tidbit at a time, for each page refresh on the right side of this blog as well… Hope you find these helpful to learn something new or to remind you of its existence and use…

#oratidbit 101: In a CDB, the UNDO_MANAGEMENT parameter must be AUTO. There is one active undo tablespace for a single-instance CDB. Cannot have separate UNDO tablespace for PDBs.
#oratidbit To create a service for a PDB using the SRVCTL utility, use the add service command and specify the PDB in the -pdb parameter. If you do not specify a PDB in the -pdb parameter when you create a service, then the service is associated with the root.
#oratidbit PDB management with Oracle EM Express is available starting with Oracle Database 12c Release 1 (
#oratidbit There is a default temporary tablespace for the entire CDB. You optionally can create additional temporary tablespaces for use by individual PDBs.
#oratidbit Specify STORAGE clause in CREATE PLUGGABLE DATABASE to specify the amount of storage that can be used by all tablespaces that belong to the PDB. Default is UNLIMITED.
#oratidbit Cluster Verification Utility (CVU) is a command-line tool that you can use for preinstallation and postinstallation checks of your cluster environment. OUI runs CVU after the Oracle Clusterware installation to verify the environment.
#oratidbit Oracle Cluster Registry (OCR) maintains cluster configuration information and configuration information about any cluster database within the cluster. The OCR contains information such as which database instances run on which nodes and which services run on which databases.
#oratidbit For a fixed-size undo tablespace, Oracle Database automatically tunes the system to give the undo tablespace the best possible undo retention. For an automatically extensible undo tablespace, Oracle Database retains undo data longer than the longest query duration and the low threshold of undo retention specified by the UNDO_RETENTION parameter.
#oratidbit Query V$UNDOSTAT.TUNED_UNDORETENTION to determine the amount of time for which undo is retained for the current undo tablespace.
#oratidbit To use Oracle Flashback Transaction Query feature, supplemental logging must be enabled in the database – ALTER DATABASE ADD SUPPLEMENTAL LOG DATA;
#oratidbit When upgrading your database, DBUA expects that both the source (pre-12c) Oracle home and the destination (new 12c) Oracle home are owned by the same user.
#oratidbit Starting with Oracle Database 12c, Oracle XML DB is a mandatory component of Oracle Database. You cannot uninstall Oracle XML DB, and there is no option to exclude it when you create an Oracle database.
#oratidbit Starting with Oracle Database 11g Release 2 (11.2), setting JOB_QUEUE_PROCESSES to 0 causes both DBMS_SCHEDULER and DBMS_JOB jobs to not run.
#oratidbit A Global Data Services (GDS) configuration and its global services are created and managed using the GDSCTL command-line interface. GDS is a highly effective solution for automatic workload management across a set of replicated databases.
#oratidbit Oracle NoSQL Database is available in Community Edition (CE) and Enterprise Edition (EE). Only EE has integration with Oracle Stack such as Oracle Database External Table Integration, Oracle Big Data SQL integration, and so on.
#oratidbit You can model data in Oracle NoSQL Database by using Tables, JSON schemas or a raw key-value interface. Tables are the easiest way to model data and they provide the highest level of abstraction.
#oratidbit Setting database initialization parameter STATISTICS_LEVEL to BASIC disables many Oracle Database features, including ADDM. Setting parameter CONTROL_MANAGEMENT_PACK_ACCESS to NONE also disables ADDM.
#oratidbit ADDM analysis of I/O performance partially depends on DBIO_EXPECTED, which is the average time it takes to read a single database block in microseconds – default is 10 milliseconds.

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